Stirring machines are commonly subject to mechanical failures relating to the operation of their down augers. Most commonly, the down auger may fail and require maintenance as a result of down auger motor failure, pulley belt failure, and overloading due to wet grain conditions. As the augers travel around the bin, there will be some unavoidable trailing of the lower portion of the auger. However, when augers bend too far from the perpendicular, the force required to move the horizontal support member around the bin becomes magnified and the likelihood of structural failure is increased.
In the known prior art, an apparatus is disclosed which includes a wheeled carriage which moves radially and reciprocally with respect to a circular grain bin on its horizontal support member. Another existing apparatus discloses down augers which are joined directly to the horizontal support member and therefore, only move in a circular fashion about the bin. In both of these apparatuses, a motor separate from the down auger drive motor is responsible for the arcuate movement of the horizontal support member. Still another known apparatus employs a single source of motive power for both down auger rotation and the horizontal support member arcuate movement which includes a solenoid controlled release clutch for the drive responsible for the arcuate movement.
Another existing system in the prior art discloses a grain bin stirring apparatus which requires less force to initiate the arcuate movement of the horizontal support member when the rotation of the down augers has first commenced. According to this prior art, the higher the rate of revolution of the down augers before initiating the arcuate movement of the horizontal support member about the grain bin, the easier it is for the motor to overcome the resistance of the grain mass. As a result, there is less wear and tear and longer life of the associated parts if the arcuate movement is automatically delayed until the auger rotation first reaches a predetermined rate. In these devices, a sail switch controls the arcuate movement of the horizontal support member and the predetermined rate of revolution of the augers. However, this device is complex, having many moving parts which are easily subject to breakdown. These parts include a spring operated switch, a circular cover plate to hold the switch in the down/off position when the auger is not revolving at a sufficient rate, and a plurality of steel balls attached to arms which are again pivotally attached to the auger shaft. Most of these parts are themselves subject to breakdown or failure due to the accumulated dust, grime and bending.
Recent advancements in the prior art provide an auger protecting system in which augers are protected using a tilt switch. In this type of system, the tilt switch measures the angle of the down augers relative to vertical. The tilt switches are initially set and then adjusted in the field depending on the grain depth, type or quality. As with the other prior art discussed above, this system suffers a number of drawbacks. First, the tilt switch can only be adjusted once the grain bin is filled. Secondly, if the tilt switch is not correctly set, the down augers will bend and break. Thirdly, the tilt switch measures an angle that is not directly correlated to the stress in the down auger and does not provide information to set the switch to protect the augers.
Based on the foregoing, there is a need for a system that adequately prevents down augers from bending or breaking. Such a needed system would directly measure the force against the down augers using springs and the like. Further, the system would allow the calculation of maximum allowable force based on the characteristics of the down auger. The present embodiment overcomes prior art shortcoming by accomplishing these critical objectives.